1. Field of the Invention
This invention concerns an arrangement for ensuring the safety of passengers standing on the steps of an escalator.
2. Description of the Prior Art
Escalators generally comprise an endless chain of treads or steps joined successively together. Severe accidents have occurred in which the foot of a passenger is caught between adjacent steps at entry or exit zones where the step chain undergoes transition from an inclined run to a horizontal run, and vice versa. A safeguard for preventing this is shown, for example, in FIG. 4 of Japanese Utility Model Publication No. 147977/1983, which will be explained referring to FIGS. 8 through 11.
These Figures show balustrades 1 disposed opposite each other (only one is visible), skirt plates 2 at the lower portion of the balustrades, an endless step chain 3 driven by means (not shown), steps 4 arranged along the balustrades between the skirt plates 2 and comprising tread plates 5 on which a passenger stands and curved riser plates 6, drive wheels 7, and driven guide wheels 8. The drive wheel shafts (not shown) are joined with the step chain 3. The tread plates 5 have a yellow caution strip 5a (FIG. 10) adjacent the riser plate 6 of the next step 4.
The drive wheels 7 are guided along a first rail (not illustrated). The driven wheels 8 ride on and are guided by a lower flanged second rail 9, which curves through the transition zones between the inclined and horizontal runs. An upper flanged float rail 10 is disposed above each second rail 9 at the transition zones. Spaced mounting plates 11A, 11B are secured to the second rail 9, and upper flanged support members 12 are secured to the respective mounting plates. Support brackets 13 are secured at their upper ends to the float rail 10, and abut at their flanged lower ends against the support members 12. Headed pins 14 extend through the abutting flanges of the brackets 13 and the support members 12. Nuts 15 are threaded over the lower ends of the pins, and retaining springs 16 are disposed between the nut washers and the support member 12 flanges. An intermediate bracket 17 is secured at its upper end to the float rail 10, and its flanged lower end engages the plunger of a sensing switch 18 mounted to the plate 11A.
In an ascending operation, the upper surfaces of the tread plates 5 adjacent each other constitute a plane at the lower horizontal entry run, form vertically spaced steps throughout the inclined run, and revert back to a plane at the upper horizontal exit run.
The float rail 10 is downwardly biased by the springs 16, and is normally supported at a predetermined spacing just above the second rail 9 by the abutment of the bracket 13 and support member 12 flanges. Under these conditions the sensing switch 18 contacts are closed by the bracket 17 flange, and the operating circuit for the escalator drive is enabled. When the chain of steps transfers from the inclined run to the upper horizontal run, the contacts of the switch 18 remain closed since the driven wheels 8 move between the confining flanges of the second rail 9 and the float rail 10, unless there is abnormality in the orientation of the steps 4.
However, as shown in FIG. 11, if the toe 19 of a passenger standing on a tread plate 5 is in contact with the riser plate 6 of the next step 4, the toe may become jammed as the vertical spacing between the adjacent tread plates 5 is gradually decreased. In this case, the tread plate on which the passenger stands drags up the next higher tread plate and attendantly raises its driven wheel 8 in the direction of arrow A. Since the float rail 10 is pushed upwardly by this displacement against the force of the springs 16, the bracket 17 also rises to open the switch 18 and disable further operation and movement for the protection of the passenger.
In a descending operation the heel of a passenger may similarly become jammed by contact with the riser plate of the step just behind or above when the chain of steps transfers from the inclined run to the lower horizontal run. An installation similar to that described above is thus provided at the lower transition zone to protect the passengers.
In such a conventional escalator safeguard system, a tread plate may also be lifted due to passenger inattention such as by sticking an umbrella tip into the gap between a tread plate and the next riser or by pushing the rollers of a baby stroller against a riser, thereby stopping the escalator and necessitating operator attention for checking and restarting. Although the yellow caution strips 5a on the tread plates are helpful, they are often ignored by passengers.